1. Field of the Invention
The present invention relates to a photoelectric composite module mounted on a board, between boards or between backplanes of an information appliance such as a router, a server and a storage device.
2. Description of the Related Art
In recent years, the amount of information handled by an information appliance such as a router, a server and a storage device has been increasing dramatically. Accordingly, a limit on the electric transmission capacity in an interconnection, between boards or in a backplane of an information appliance has become obvious. An interconnection technique that uses an optical transmission is a common method in the industry to solve these problems.
A logic LSI configured as a low cost and compact input/output device using an optical interconnection is known in the industry as a means to perform signal processing and to use a photoelectric composite module for an input/output interface. The photoelectric composite module has an optical device, a driver IC and a circuit board for mounting the optical device and the driver IC by flip chip bonding as basic components. In addition to a layer-to-layer wiring formed on the circuit board, a wiring pattern is also formed on both sides of the circuit board.
A conventional technique using such a photoelectric composite module includes those described in the documents below, for example.
Japanese Patent Laid-Open No. 2003-185891 proposes an optical receiving device in which a photoelectric component such as photo electric device 11 and semiconductor device 10 or the like that adjusts the current amplitude of the optical device is implemented on circuit board 14 by a flip-chip bonding as shown in FIG. 2 in the document. The device is fixed by metal bump 18. Optical connectors 15 and 16 are attached to and detached from a fixed device.
Japanese Patent Laid-Open No. 2004-31508 proposes photoelectric composite module 6 in which optical device 61 and driver IC 62 are connected by a flip-chip bonding to electrode 66 on transparent plate 13 on which a wiring pattern is formed. Driver IC 62 is electrically connected to a board mounted with a module via layer-to-layer wiring 69 of transparent plate 63 and a via member. In order to adjust the height of an optical axis according to the height of the rack in which a board is housed, module 4 having optical axis converting device 44 with a mirror as shown in FIG. 4 in the document is also provided.
Japanese Patent Laid-Open No. 2003-207694 proposes an optical module in which V groove 6 for positioning optical fiber array 7 is formed on connector 5 that is attached to package 1 and mirror 9 tilted by 45 degrees is arranged at the end of optical fiber array 7. The light outputted from light emitting device 2 of package 1 is reflected on tilted mirror 9 via lens array 4 and its optical path is bent by 90 degrees and then input into optical fiber array 7 as shown in FIG. 2 in the document.
Because optical connectors 15 and 16 are attached or detached to and from a device fixed to the board or the like according to the technique described in Japanese Patent Laid-Open No. 2003-185891, a channel for attaching and detaching them needs to be previously reserved on the board. Therefore, other electric components cannot be arranged on the channel for attaching and detaching optical connectors 15 and 16. From the standpoint of the implement layout, it is not desirable that such a dead space be present on a board.
Because via member 69 intervenes in an electric connection between driver IC for input and output 62 and the mounted board according to the technique described in Japanese Patent Laid-Open No. 2004-31508, a high frequency property may be degraded. Since the direction to which heat is released from the optical device and the driver IC is limited toward the board on which they are mounted, the layout on the board is not simple.
The techniques described in FIG. 4 of Japanese Patent Laid-Open No. 2004-31508 and Japanese Patent Laid-Open No. 2003-207694 require optical path converting means by a mirror or an optical coupling means by a lens between an optical connector to be attached or detached and a light receiving/emitting element. This leads to a problem in which the number of members and the number of processes are increased, and this raises the cost of implementation.